iio: light: vcnl4035: fix information leak in triggered buffer

BugLink: https://bugs.launchpad.net/bugs/2097298

commit 47b43e5 upstream.

The 'buffer' local array is used to push data to userspace from a
triggered buffer, but it does not set an initial value for the single
data element, which is an u16 aligned to 8 bytes. That leaves at least
4 bytes uninitialized even after writing an integer value with
regmap_read().

Initialize the array to zero before using it to avoid pushing
uninitialized information to userspace.

Cc: stable@vger.kernel.org
Fixes: ec90b52 ("iio: light: vcnl4035: Fix buffer alignment in iio_push_to_buffers_with_timestamp()")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20241125-iio_memset_scan_holes-v1-6-0cb6e98d895c@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>

Author: javiercarrascocruz

drivers/iio/light/vcnl4035.c

@@ -105,7 +105,7 @@ static irqreturn_t vcnl4035_trigger_consumer_handler(int irq, void *p)
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct vcnl4035_data *data = iio_priv(indio_dev);
 	/* Ensure naturally aligned timestamp */
-	u8 buffer[ALIGN(sizeof(u16), sizeof(s64)) + sizeof(s64)]  __aligned(8);
+	u8 buffer[ALIGN(sizeof(u16), sizeof(s64)) + sizeof(s64)]  __aligned(8) = { };
 	int ret;
 
 	ret = regmap_read(data->regmap, VCNL4035_ALS_DATA, (int *)buffer);